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To what extent have political (race, gender, social class) attitudes been implicated as human factors in the cockpit?
This question is related to:

How does cultural difference impinge upon human factors in aviation industry safety?
How have deep-seated cultural human factors (particularly in east Asia) in the cockpit been successfully managed in the past 20 years?

Standard industry practices of cockpit management can invert or disrupt very deep cultural and political expectations of command and authority.
The question
What evidence is there, in research, incident reports or other documented sources, that has identified political attitudes around race, gender or social class as human factors in the cockpit?
For example:
With more women in airline cockpits, have new human factors emerged (for example, a male pilot displeased to be questioned by a woman)?
In regions with troubled racial histories (southern Africa, the USA) have race relations and attitudes in the cockpit been responsible for incidents?
In cultures where social class or even caste is very significant, have these been implicated as human factors in the cockpit?

I know of a situation where a male pilot (FO) was very displeased with a female Captain (who was PNF at the time) adjusting power on short final without following the normal process for taking control of the aircraft and, as a result, crashing the aircraft into the runway. However, this (both the crash and the FO's [and airline's, NTSB's, and FAA's] displeasure) seemingly had more to do with her being an arrogant jerk who flaunted SOP than being a woman. Needless to say, she was fired.

Could that be answered factually? It seems to call for individual opinions and non representative events.

@mins Possibly. Accident reports do list these sorts of things as contributing factors.

@fooot Even so, accident reports are, by nature, discussing non-representative events. That said, I don't recall any accident reports where race, gender, or social class made any difference... unless you count a GA accident report where the people in the front seats were of opposite gender and investigation of the crash scene indicated that they were engaged in activities other than flying the aircraft.

How is this "opinion-based"? I'm not asking whether some random person has opinions about any of these things; I'm asking whether research has identified new human factors emerging, whether incident investigations have implicated race attitudes or relations in their reports; whether social class has been implicated in incident investigations. Whether or not this is the case fact. Even if you completely disagree with any such reports or research, it's still a fact that these factors were implicated (or not) in them.

This question seems too broad.  Possible more specific questions include "does gender play a role in the perceived importance of cockpit communication,"  "are lower class pilots less likely to challenge their partner's authority,"  "How many accidents have had race as a contributing factor," "What is being done to compensate for strong social class differences when implementing CRM" or even "how do they select the gender of aural annunciations."

I don't have the time to write an answer right now, but I encourage you to check out Korean Air Cargo Flight 8509.

@DanieleProcida I think this is an opinion-based question because any research about the relationship between "attitudes" (of people, not planes) and piloting would be opinion-based research.  Just because it's documented expert research does not mean there are no opnions.

There are numerous accident reports that state cultural issues as contributing factors, especially respect for elders / superiours / social class in Asian countries leading to poor "Crew Resource Management" - typically the co-pilot failing to challenge the captain.
The first examples that come to mind are:

https://en.wikipedia.org/wiki/Korean_Air_Cargo_Flight_8509 - According to the Mayday episode, the captain was of a higher social class than the co-pilot.
https://en.wikipedia.org/wiki/Korean_Air_Flight_801
https://en.wikipedia.org/wiki/Air_China_Flight_129

The Air China 129 wiki article does not mention social class as a factor. That might appear somewhere in the crash reports, though? They better link would be nice.

As a aeronautics and space student, I can tell you that there are standards(especially US military standards) for the configuration of the cockpit.wethear the hight of the seat and the length of the arm( it is needed to know if the pilot can reach all devices without struggle). You are right, there are many different people with different body shapes and sizes. however, the aircraft manufacturers have standards and pilots who don't fit the standard have it a little bit difficult. Moreover, if you might notice military pilots are picked carefully to match the standard, since a pilot needs to fit in the best way to the plane so he will be focused on flight rather then comfot. To answer your question, there are no modifications special for race or gender, unless you build a  customize plane.

You seem to have missed the point of the question, at no point does it ask about ergonomic standards, which is what your answer is about. The question is about social, cultural and political disagreements in the cockpit.

I answered you both in the technical part of engineering. Since you are interested in the social part,  there is racial and gender bias everywhere... So where there is bias the aviation company will have bias as well so it will hire according to that bias.

I understand what you answered, the issue is that it does not answer the question as asked, and on this site we prefer answers that stick to what was asked, or at least address the actual question before going off on a tangent.

Since the 1970’s, it appears that more republicans than democrats have been involved in fatal aircraft crashes that they are the pilot in. There is a partial list of political affiliation in aircraft crashes at the political graveyard:
https://politicalgraveyard.com/death/aircraft.html
Recent crashes include GOP State Senator Doug Larsen, killed after stopping to refuel his plane.
https://apnews.com/article/a7064a4f3a883be6f920fb647d10c6ca
There is no data comparing the number of Republican to Democrat pilots, so it is not currently possible to determine if political affiliation can be linked to deaths, but one can see that more (R) pilots seem to die than (D) pilots.

One has to account for proportion and age, though. Modern Republicans tend to be older on the average, and among the older ones, better-off than same-age Democrats.

The question is asking about evidence of this as a human factor in the cockpit. There is no evidence of any sort of causal factor here.

It would help if you would include actual numbers. I looked at the Political Graveyard link that you provided, it's pretty tedious going through each bio to find out if they are Democrat or Republic since it's buried in the text for each one. I started in 1972 through present and I counted 13 Democrats and 8 Republicans.  Maybe I went through it too fast, what numbers did you come up with? Are  you sure there is enough of a difference to see any kind of trend?


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Why didn't planes land from the sea in the old Kai Tak Hong Kong airport?
Reading up on the old Hong Kong airport Kai Tak, I'm left with the question as to why the planes didn't land from the sea?
I know that takeoff was done towards the sea, but is there any reason that you couldn't land from the same direction you take off? Or is this less feasible due to traffic?
It otherwise seems to me that largely congested airport areas could (have) benefitted from bi-directional use of the runways. And I don't think wind direction could have made much of an impact for Kowloon, given the mountains and skyscrapers everywhere.
This question seem to suggest that landing and takeoff in/from the same direction is not standard in aviation, but with very limited details.

The issue is wind, you always (usually) want to take off or land into the wind. So yes, you always (usually again) want to take off/land in the same direction. I'm not sure why you would say it isn't standard, it is very much standard.

I meant landing from west and takeoff towards west, rather than takeoff towards east (as an example).

you want to face in the same direction for both takeoff and landing, because the effect of the wind is the same. if the wind comes always from the sea, you will takeoff/land always facing the sea, as also the answer you link says.

@RonBeyer Seems like you have a concise answer there, why not make it an answer?

Simply because it is less excited than the world-famous 31 approach so it is hard to find photos/documents. In fact several incidents like CAAC Flight 301 happened when landing on runway 31.

Why do you think wind direction wouldn't have "made much of an impact?" The mountains and buildings may have had an effect on the wind, but there were still winds, often fairly strong ones, and they often favored Runway 13.

I don't know what you are asking.  Take offs and landings were carried out on runway 31 too.

Unofficial plates for approach ILS RWY 31, from VACC. Note the checker board hill was also painted on the south facing side.

Reading up on the old Hong Kong airport Kai Tak, I'm left with the question as to why the planes didn't land from the sea?

It's a small point, but Kai Tak was not next to the open sea but rather alongside Victoria Harbor. Most of the rwy 31 final approach was over the harbor but with mountainous terrain on either side. The rwy 13 final approach was over Hong Kong island, then Victoria Harbor, then Kowloon.
Both rwy 13 and rwy 31 were used for takeoffs and landings depending on the wind, and winds in Hong Kong were often strong right down to ground/water level. Generally the prevailing winds favored rwy 13. By that I mean that when tracking the runway just before touchdown or when taking off you would have a headwind component. However, because most of the time there was a crosswind, it often meant that when approaching for landing but before you made the 47 degree right turn from the IGS course to short final, you had a tailwind component.
Both runways could be very turbulent. If ceiling and visibility were poor, that always meant a rwy 13 approach, at least that was my experience. The worst turbulence, though, was in severe clear conditions to rwy 31 when the wind was coming off the Chinese mainland.
I have a blog item about operating into Kai Tak on my website. You can look at it here.

Here is an overly simplified diagram of the operations around a runway:

(Source: Quora)
As you can see, aircraft land and take off in the same direction. This is to keep the aircraft into the wind.
Related: Why is tailwind during final approach and landing so dangerous? Much of the same argument goes for taking off too. Taking off with a tailwind you need to have a faster ground roll to get the same airspeed to take off. This increases the time on the ground and uses up valuable runway in case of an abort.
The other problem as you hinted at is traffic. Pointing aircraft taking off at aircraft landing requires a much greater distance between the two so the outbound aircraft can turn to avoid the inbound aircraft. When you are closing at high speed (usually above 400kts), the separation requirements are used up pretty quickly and you need to space them out farther. It's also like playing chicken with hundreds of passengers, not something you want to do.

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Can planes benefit from Mitsubishi's Air Lubrication System?
Mitsubishi's Air Lubrication System blows a fine sheet of bubbles below the hull of a ship. The bubbles form a "carpet" on the hull, reducing friction. See Gizmag (yes, sorry) for some more information.
Let's assume that such a similar mechanism - something like the surface of an air-hockey table perhaps - would be feasible to implement on an aircraft.
What aerodynamic effect would it have? Could it, assuming it were feasible, provide any benefit to an aeroplane/helicopter/dirigible?

I think the best approximation for this on airplanes would be vortex generators.

@SMSvonderTann what about plasma actuator?

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Could the experience of inflatable structures in boats be applied to large aircraft design?
Inflatable structures in boats have proved extremely successful and versatile since they began to find widespread use in the 1930s.
I'm aware that experiments have been made with inflatable wings - very light, delicate structures mainly on human-powered and unmanned aerial vehicles.
On boats, they're used differently: in some cases they form the main structure of the craft itself, in some, the craft has a rigid hull and the rest of the structure is inflatable, but either way, the inflatable sections are very far from delicate.
Experience gained with multiple air cells in inflatable engineering means that it's now possible to build effectively rigid structures, that are extremely tough, reliable and resilient. Their behaviour in failure modes is well-known.
Many large aircraft have built-in air compressors - the engines - that could keep the inflatable structures correctly pressured at all stages of a flight.
Materials science has produced enormous improvements in the longevity and resistance to chemicals/sunlight/temperature ranges of the rubber skins of inflatable structures.
What opportunities are there for designing parts of an aircraft as inflatable structures (perhaps winglets, or undercarriage doors)?
Is there any research or experimentation into more heavy-duty use of inflatable engineering in aircraft?

If you're inflating the structure with air what would be gained from doing so? Inflatables in water craft are desirable due to buoyancy. That would not apply in aircraft.

@TomMcW Compact storage?

@TomMcW Light weight would be the main one. Inflatable structures also have different modes of extension and collapse, compared with rigid ones, that might be potentially  useful.

Wings are usually inflated with liquid fuel, and the fuselage must be pressurized at a level comfortable for occupants, so I'm not understanding what part of the structure might benefit from being inflatable.

We now have experimental use of inflatables in space as well as for boats.
If an aircraft's engines are responsible for the inflation of any aerodynamic or structural part of the aircraft, however, one would have to answer what happens if the engines stop. A conventional aircraft whose engines fail at a sufficiently high altitude can glide for some time, giving the crew a chance to restart the engines; it may even be landed without engine power if necessary. This is a very bad time for the aircraft to lose aerodynamic performance or structural strength--for example, for the winglets to deflate just when the crew need the best possible glide slope.
Unlike boats or spacecraft, moreover, most conventional aircraft are intended to descend from altitudes of low pressure to altitudes of high pressure. If the amount of gas in an inflatable structure is held constant, one has to balance structural rigidity at low altitudes against the stress on the fabric from the much greater pressure difference at high altitudes. If the amount is not constant, it has to be replenished during descent. The engines cannot be relied on to do this, since the reason for descent may be engine failure. Gas could be supplied from high-pressure cylinders, but those can be heavy.
For an aircraft not intended to climb very high, these concerns are less severe.

It has been done:  https://en.wikipedia.org/wiki/Goodyear_Inflatoplane
It was intended as something that could be dropped to pilots behind enemy lines for escape purposes.  Never got popular as if the pressure dropped the structure failed.

Not very practical as an airplane, but lack of space in fighters was the bigger issue than damage suceptibility.  The bundle was fairly bulky and heavy.

In a way, aeroplane structures have pioneered using pressure differential for structural benefit. The fuselage of an airliner is under pressure and functions as a pressure vessel. In flight, the fuselage is supported by the wings - nose and tail want to sag down from gravity forces, creating tension in the upper section and compression in the lower section.
Compression stresses require reinforcements against buckling, and structures can be constructed lighter if compression forces are reduced. And this is what the internal air pressure does: it pre-loads the fuselage structure under universal tension stress. Compression stresses at the lower fuselage segment are considerably reduced, or replaced by a reduction in tension forces.
Inflatable structures are beneficial because of the elimination of buckling: flimsy plastic that buckles in all directions will obtain universal stiffness when under tension stress from the inflation pressure, and this is where potential weight gains could be obtained. But without the air pressure the structure would collapse, and this is where the concept might not be very suitable for aeronautical purposes. Safety.
The overpressure in an airliner fuselage is an essential design demand for the passengers to be able to survive the conditions at cruise altitude in reasonable comfort. But introducing a potential failure point only to save weight is a different matter - I'm not saying it could not be done, but it would require a large effort in safety analysis.

A paraglider (or powered parachute or powered paraglider) is an example of a popular style of inflatable aircraft.
Their behavior in failure modes is well-known-- in the paraglider case, many pilots have had the pleasure of experiencing it first-hand.
(Ok, I see you specifically said LARGE aircraft design.  Sorry for the side-track... )


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Have we seen the last significant experiments in the configuration of jet airliners?
By the 1940s, passenger airliners had pretty much settled down on the shape that has dominated the industry since then: a monoplane, with wing-mounted engines, a roughly cylindrical single fuselage and a tailplane.
The 707 set the template for jet airliners: low wings, and pylon-mounted engines.

Source: Wikipedia
Apart from the few, smaller, models that place their engines on the rear of the fuselage, there are almost no models currently in production that adopt a different template (in fact, the only one I am aware of is the Antonov An-148).
There are no more tri-jets. There are no more radical experiments like Concorde on the horizon, never mind in production. There are no serious proposals for significantly different shapes or configurations.
The only significant configuration choice for medium-to-large size airliners seems to be two engines or four.
Since the 707 slung its engines under the wing on pylons in the 1950s, the only significant development that I can think of is the adoption of winglets in the 1980s.
You might consider the 747's hump and the A380's twin decks to be significant variations, but they are still only variations on the theme, not fundamentally different configurations.
Assuming that jet engines remain viable in 40 years' time, will the airliners of 2058 still look fundamentally like 707s?
If you're concerned that question seems too open to mere speculation, let me ask it another way: is there a fundamental design reason why the low-wing/pylon-mounted engine/cylindrical fuselage/tailplane configuration established by the 707 shows no sign of being displaced by alternatives?
Or, why have the enormous advances in (for example) materials and aerodynamics made so little difference to the fundamental shape of airliners?

With current fuel prices: Yes, we have arrived at a mature design which will not change much. Recent trends like the increase in aspect ratio and engine bypass ratio will continue, but the general arrangement will remain unchanged.
Just look what happened in the first 50 years of airline operations, and how much changed after that in regards of aircraft configurations:

If fuel prices rise to 200 USD per barrel and more, expect slower airliners with less sweep, much higher aspect ratio and probably even braced wings. To enable bracing the wings will be mounted on top of the fuselage, like on the Hurel-Dubois HD.31.

Boeing SUGAR Freeze concept. Note the third engine in the back which ingests the fuselage boundary layer, thereby reducing separation and pressure drag.
While you might read about two more new design directions, a supersonic airliner and the blended wing-body (BWB), I am rather skeptical that any of those will be adopted in the future.

Why braced wings?

@CarloFelicione because the wing in that proposal is very thin and not strong enough to support itself.

A new design driver that could change the look of future aircraft is noise. In order to reduce noise, engines could be integrated in a way, that the ground is shielded from the noise during takeoff and landing. Also, a higher emphasis on aeroacoustic interference could have a small impact on design.

@FelixL. This design driver is also 50 years old by now. Placing the engines above the narrow wings will not achieve much; going with a geared fan looks more promising. Of course there will continue to be minor tweaks, but the general layout will not change unless fuel prices go through the roof.

There is plenty of desire to push aviation. Since the Concorde was retired, there has been a desire to pursue a second-generation supersonic aircraft. The problems to launch something, you‘re going to spend billions of dollars. How do you recoup those monies to avoid another Concorde moment of creating something fantastic that has no hope of breaking even.
An example would be the Boeing Sonic Cruiser. This was a concept jet airliner with a delta wing-canard configuration. It offered a slight increase in speed, a carbon fiber shell with fuel efficient engines. Most airlines favored lower operating costs over a marginal increase in speed, so Boeing went with a slower design which became the Boeing 787 Dreamliner. Boeing has other supersonic ideas in play as well.

For nearly twenty years, EADS — the parent company of Airbus announced that it was considering working with Japanese companies to develop a larger, faster replacement for Concorde. The concept is a plane that carries 300 passengers at mach 2 with a per-seat ticket price comparable to flying subsonic speeds. I have not heard much lately about the concept.
Lockheed would like to get back into commercial aviation and has been working with
Supersonic Aerospace International on a Quiet Supersonic Transport. This plane would seat 12 passengers, cruise at Mach 1.6 and create a sonic boom only 1% as strong as that generated by Concorde.

Boom Technology is an American startup company designing a Mach 2.2 (1,300 kn; 2,300 km/h) 55-passenger supersonic transport with 4,500 nmi (8,300 km) of range, to be introduced in 2023, called Overture. TBoom is hoping to power the Overture with three moderate bypass turbofans without afterburners, unlike Concorde's Rolls-Royce/Snecma Olympus. The issue is finding a non-military efficient engine.

If you search out some of the concepts just over the horizon, you will find lots of great ideas and concepts. It's just a matter of figuring out a market to recoup development costs.

There are decade worth of conceptual aircraft, and the ones you cite seem no different. What makes you think any of these are feasible, let alone have the potential to become mainstream?

Boeing never stopped Sonic Cruiser development.  In the last 18 years, they keep announcing updates, worked with NASA on a demonstration aircraft. There's no customers requesting it, so there's no plans to build a production model. Boom has collected $150 million in funding and will have a demonstration model flying this year and production starting in 2023. Things are slowly moving forward.


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Why has aluminium, rather than steel, prevailed in airliner construction?
As any cyclist knows, steel has many advantages over aluminium:

it's stronger (for the same size)
it can handle greater forces without needing to be stiffer
it has better fatigue characteristics
it's easier to work with
and most importantly of all, it offers a more responsive and comfortable ride.

On the other hand aluminium is much lighter (for the same strength), which obviously is pretty important in an aircraft.
Even so, steel-framed bicycles aren't always heavier, or significantly heavier, than aluminium-framed bikes of similar strength, and in engineering the strength of a construction is not only determined by its materials, but also its design.
When did aluminium become the default material for the vast majority of an airliner's construction, and is its strength-for-weight advantage the principal reason?

I'm not sure the steel-vs-aluminum bike is a good analogy. You may be comparing apples and oranges, for example if an aluminum bike weighs 10lbs and the steel one weighs 12lbs, that isn't a significant weight, but look at percentages, its 20%. Take an aircraft weighing 20,000lbs, 20% is another 4,000 lbs...

I disagree on the fatigue point: Aluminium is outright nasty. Steel is much more forgiving.

@PeterKämpf Which fatigue point?

I think the expression intended is fatigue limit. Aluminium does not have a fatigue limit, that is why it's so nasty.

You are right, on first sight it is actually surprising that aluminium prevailed. It comes with some disadvantages:

Crack growth must come first in this list. With only a small cyclic load, cracks in aluminium will relentlessly grow. This requires frequent checks and has caused many accidents. Fortunately for aluminium, this fact was only discovered after WW II when the lifetime of aluminium airframes shot up from dozens to thousands of hours, so aluminium was already firmly established as the premier structural material.
To connect two aluminium parts, only riveting or bolting are available. Recently, bonding has become viable, too. Steel offers a third choice in welding, which gives it the advantage in vehicle construction. Again, history gave aluminium a head start, because when the first metal airframes were designed, welding was still relatively little developed, so the restriction to riveting was not felt as the disadvantage it is.
Corrosion: Here it is generally better than steel, but far worse than stainless steel which would be the prime candidate (next to maraging steels) for airframes were aluminium not available. During the Berlin Airlift, salt or baking powder could only be transported by seaplanes because it would had permanently damaged the landplanes. Seaplanes used special, corrosion resistant alloys which were needed in the marine environment.

In the end, however, this is still outweighed by the principal advantage of aluminium: Its low density. This allows to use thicker gages for the same weight, so the buckling strength of aluminium skins is far better than that of equally heavy steel skins. In aviation, the demands of aerodynamics make the use of crimps or reinforcing seams impossible, and only the labor-intensive addition of closely spaced stiffeners could remedy this. Such a stiffened steel skin would still be inferior when it comes to hail damage or handling loads, though, so aluminium was the obvious first choice.
In order to keep material cost down, Junkers built his first metal aircraft from steel but had to switch to corrugated aluminium in order to make them light enough. Note that the structural integrity of his designs was ensured by a steel truss, and only the covering was from corrugated aluminium. Later stressed-skin designs did away with the steel truss.
To compare the strength and stiffness of different materials independent of their density, you can use their breaking length and specific modulus, which can be expressed as their strain length. Surprisingly, most structural metals have a comparable value and only composites can set themselves apart.
Despite its nasty failure characteristics, aluminium has defended its position as the dominant structural material: By the time composites were developed, the engineers and certification authorities had learned how to handle aluminium and had created a barrier to entry in the form of a host of tests and approved construction techniques which severely harmed composites. If all the materials we know today had been available a century ago, aluminium aircraft would had become an oddity, not the norm.

Wikipedia has a page on specific modulus, which appears to be the same thing you are calling "strain length" (= Young's modulus per density). It never mentions the "strain length" term there.

@JanHudec Strain length is a theoretical term: The length of a vertical rod hanging under its own weight where the top doubles in length from the strain. This gives a very descriptive figure which is totally unrealistic. You are right, the page lists what I mean. I edited the answer accordingly.

I may be missing something, but isn't aluminum repair easier than composite repair, or repair on steel, due to lower hardness in the latter case ... or is that too broad of a statement to classify as a pro or a con?  The design criteria of "maintainability' has entered the field (it was certainly a criterion for the F-18) but maybe not so much for other models?

@KorvinStarmast: That is a hot topic. I have done several composite repairs on gliders and find them much easier to repair than a metal structure. The toughness of stainless steel is a drawback, granted, but then weldability is a huge advantage. With metal, if you do it right, you better replace a part completely.

OK, I have a few friends working composite repair for UAV's, but that's another topic.

Good strength to weight ratio, manufacutrability, resistance to corrosion, have been the driving factors behind the use of aluminum alloys.  However steels are used in high strength applications such as the landing gear.  Stainless steels has been used in a few airframes such as the MiG-25 for their higher yield strengths when heated.

It really comes down to cost/benefit.
Let's consider two aircraft that were built out of stainless steel, and performed very well: the XB-70 and X15. Stainless steel was used to resist the heat of Mach 3+ flight, which would weaken aluminum to a failure point. At the time the XB70 was originally designed, titanium wasn't available in sufficient quantity to consider a large (100+ airframe) production run.
The X15 did achieve a speed of Mach 6.7, where skin temperature would be quite high. However, it was a pure research rocket powered aircraft, so it doesn't make as appropriate a contrast, and that speed was maintained only briefly.
By the early 1960's, titanium was available in enough quantity (albeit by using shell corporations to purchase it from the Soviets) to build the smaller and less produced A12/SR71. Like the XB-70, it was designed to sustain Mach 3+ for over an hour, and the subsequent high skin temperatures that preclude the use of aluminum.
The key issue to understand here is sustained Mach 3 flight: for over an hour. Aluminum interceptors such as the MIG25 have a brief Mach 3 dash capability, five or ten minutes, where the skin temperature won't rise as much. After ten minutes at Mach 3, the MIG25 is very low on fuel and it's engines are ruined.
To keep weight low, the XB70 used a complex honeycomb design that is expensive to manufacture, and the resulting aircraft still was heavier than an aluminum aircraft of similar size. The XB70 made up for this by using compression lift - literally riding it's own supersonic shock wave - for very efficient Mach 3 flight. The A12/SR71 used the shock wave in it's engines to achieve a similar level of efficiency.
Note that the B-58 also used a honeycomb construction to keep weight low, but was made from aluminum, as it's design speed was Mach 2. The Concorde was made from aluminum, but it cruised at Mach 2.2. Beyond that speed, the heat generated from skin friction rises dramatically, to a level where aluminum would be critically (and fatally) weakened.
Presumably, a commercial aircraft made from stainless steel would also require the complex honeycomb design to achieve a reasonably efficient weight. It would still not be as efficient as an aluminum aircraft. As the primary reason not to use aluminum was to resist sustained Mach 3 heat, a speed that only the SR71 and XB70 can maintain for any period of time, the extra expensive of honeycomb steel (or titanium) and the greater weight isn't really justified for a subsonic airliner.
The XB-70 was canceled as it was thought to be vulnerable to the SAM2 missile the Soviets had developed. Ironically, the SR71 proved this not to be the case: being shot at over 1000 times (including many SAM2's) and never hit.
Yes, you can build an aircraft out of stainless steel. But, the honeycomb construction is expensive, and the result less efficient than an aluminum aircraft. The only reason steel was used in those two aircraft was to sustain very high skin temperatures. You could build one out of titanium, and it would be even more expensive.
While there have been airframe failures from aluminum fatigue, countermeasures far less expensive and lighter than moving to stainless steel have been developed.

Aluminum has a worse fatigue behavior than steel, but it has two important advantages: strength to weight ratio and corrosion resistance. In the beginning of aviation there were some aircraft made of steel. Some of the engines in that era also had cast iron blocks. But the resulting weight was terrible. As for corrosion resistance, see for yourself: you still see 45-year old Boeing 727's at airports with their airframes shining like new!


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What do we hear, on the ground, from a helicopter in flight?
Last week I heard a helicopter approaching from a distance.
The sound it made was a very distinct and deep wop wop wop at a remarkably slow two beats per second, more or less.
As it came closer, the sound suddenly changed, to something more like six beats/second, with a quite different and more familiar chattering.
What were we hearing from the ground? What do the two different sounds represent?

It's super super super dependent on the specific design of the helicopter - a 50 year old Huey cobra sounds SOOooo much different than a modern chopper with a shrouded tail rotor.  TL;DR is below.   ;-)

What type?  A lot of noise comes from the blade tip vortexes interacting with each other, particularly when turning with a low rate of descent.  The tip of each blade can strike the vortex left by the previous blade.  Chinooks are famous for the "wop wop" as the vortex from the rear blade moving down strikes the forward blade going in the other direction.  Overall, as others have said, helicopter noise in general is a very complex area.

Rotor noise is relatively complicated, and is very highly dependent on the design of that particular aircraft. Here are at least a few components to consider:
Ultimately what you're "hearing" is of course pressure waves in the air, which in a helicopter are almost entirely caused by the rotors passing through said air[1].  If you're head-on and a fair distance away, you're primarily hearing the pressure wave that's generated as the rotor passes the point where it directly points at you, because that's where you get the strongest component of pressure "pointed" in your direction.
As the aircraft moves, your orientation to the sound profile changes: you get both the doppler effect which changes the pitch, but you also get a very different sound profile because the pressure waves from the main rotor are interacting with both the body of the aircraft and more importantly the pressure waves from the tail rotor in different ways.  I don't remember the exact percentage, but a very large part of the sound generated by helicopters is the interaction of the main and tail rotors - this is a main reason that you see a lot of modern helicopters with a "shrouded" tail rotor. If you're truly head-on, it's reasonable to assume that you're getting very little of the interference with the tail rotor, and as you get more side-on with the aircraft you get far more interference noise.
[1] You also, of course, get noise from the engine-- but that's usually drowned out unless you're quite close, OR if you happen to be sitting near a chopper with the rotor at zero-lift... in this case the noise from the rotor is actually pretty low and you can hear the engines and the tail rotor a lot more clearly...


text:
What role, if any, does visual aesthetics play in the design of modern airliners?
Another way of asking the question:

Are there any distinctly identifiable features of particular modern airliners that are there for design reasons that have less to do with engineering than with appearance?

or:

Could one look at at a modern airliner, and point out something in its design, however small or large, that is there because "it looked good"?

To be clear about a few points:

By modern I mean since the 707.
In visual aesthetics I only want to include physical form - contours, placement of parts, proportions etc - and specifically want to exclude livery, colour, and so on.
I'm not interested in inessential matters like the design of the interior, but in the airframe, engines and so on.

I'd be pretty surprised to discover that any aspects of design allowed aesthetics to trump engineering consideration, but perhaps there are examples where aesthetics played a part because the choices, from an engineering point of view, were equally viable.

Does the paint job count as one ?

No, I specifically excluded that in the question.

@Peter Kämpf mentions the following:
Boeing engineers spent several months on optimizing the fuselage-stabilizer intersection of the 767, only to have one manager impose a different geometry "because the optimized one looks like McDonnell-Douglas"  in a comment to this answer, so it seems that people do make choices based on aesthetics

I think the "shades" appearance of the 787 windscreen has some consideration for aesthetics

Oops, it was the A-350, not the 787 I was thinking of

A friend of mine, who did the design of the Gulfstream G650 canopy, designed the cockpit windows on that jet after the lines of an Aston Martin sports car.  I suspect there are a few other features like that in various aircraft.
That being said, despite the aircraft design mantra of 'if it looks good it will fly good' most the the design choices made in aircraft is very utilitarian.  Aerospace engineers - and in particular the management at the major OEMs - are some of the most boring, unimaginative SOBs you will ever meet.  They generally leave creativity to the marketing departments and make every effort to pound flat any nail that sticks out.
The only exception to that rule that I can think of was Burt Rutan of Scaled Composites, who when his own way and designed unique planes as virtual works of art - but also were highly functional with great performance and capabilities.  From the Vari-EZ to Spaceship One, that guy is in a league of his own.

For the record, flat nails exhibit far less drag than ones that stick out.

For the record, Burt Rutan was much better at marketing his designs (and himself) than at engineering them. Just witness what happened to his over-hyped Starship design.

Well the Starship’s problems weren’t related to performance.  Rather it was associated with the expense and complexity of manufacturing an all composite aircraft, same as with the LearAvia LearFan.  The end result was a product that cost as much is a jet but only delivered turbo prop performance. That won’t sell too many units.

You may want to check out this article.
Function aside I agree with them that to me the Boeing nose has always been more pointed than the airbus nose.
Airbus Nose

(source)
Boeing Nose

(source)
There is of course engineering decisions for this decision, but as to which one is the "correct" way to build a nose you may not find an answer.
Depending on if you consider the cockpit "inessential" since its an interior part of the design there are some very easily identifiable cockpit features when we are talking about the Boeing/Airbus comparison.
If we look over at small planes, the most identifiable feature that I can think of is the inverted shaped rudder on almost every Mooney ever produced. Some think this was done for esthetic reasons but there are actually lots of aerodynamic reasons Al Mooney chose the design.
Since you put the hard cut at the 707, you will get mostly planes that were designed in the modern age where function over form ruled and our knowledge of aerodynamics was far beyond what it was in the 50 years before that. Earlier planes, designed in an era when aerodynamic knowledge was far less are more likely to have "just for esthetic" things.

I can't speak much to airframe design, but I can say that in the case of the engines, basically zero consideration is given to aesthetics. Some of the designs do end up looking quite visually appealing (e.g. GE90 fan blade in Museum of Modern Art). However, that is entirely a happy coincidence. The biggest three concerns are fuel burn, weight, and cost. Fuel burn is such a huge driver that if the choice were between A) hideously ugly design that made fuel efficiency better by 0.001% or B) beautiful elegant design that made fuel efficiency worse by 0.001%, option A would win every time hands down.
The only engine feature where aesthetics might be given some consideration is the paint scheme on the front of the spinner, but you said you weren't considering paint.

There is a saying in aviation that mainly applies to the entire craft but also applies to bits of it, like turbine blades.  "If it looks right, it probably is right".

Winglets may be a good example. Not entirely aesthetical (hardly anything in aviation is), but the undue attention given to them is certainly driven more by the look rather than use.

They are quite useful in reducing vortexes etc ...

Winglets effectively extend the area of the wing without physically extending it. These make the wing produce more lift and less drag, resulting in fuel savings. They are very much functional designs. Winglets are the embodiment of "form follows function".

@D.Clayton, they are not "quite useful", they are slightly useful. But my point is that what governs their shape (and even presence, to some significant extent) is largely driven by aesthetics rather than aerodynamics. Ron's comment about not extending the wingspan is more valid, but it only applies when there is an actual restriction on it (which is the case for e.g. A380, which got small fences instead of A330-style winglets). Aerodynamically, it's always better just to extend the wingspan.

@Zeus, aerodynamically extending the wing is better and that is why winglets almost never appear in first iteration of any design. However for upgrades and retrofits extending the wing would require redesigning the whole wing with stronger spar due to the increased root bending moment, while winglets can often be retrofitted, because their effect on bending moment is smaller. That's why they often appear on later iterations of designs.

@Zeus, the undue attention given to winglets is mainly marketing taking advantage of how they look. But engineering chose them as cheap way to squeeze a bit of performance first and marketing bloated the benefit next.

authors: Γιάννης Μιχαηλίδης


text:
What determines the noise an aircraft's undercarriage makes at the moment it leaves the ground?
In an Embraer E170 at take off, there is only the faintest clue from the undercarriage that the wheels have left the ground.
In a Fokker F70, there is by contrast a loud mechanical "clonk" that can be heard and felt very distinctly.
What's different in the design of the undercarriage in these aircraft? And what's going on in the F70 that some component of the machinery is walloping around enough to produce such a noise?

Difference in hydraulic shock absorbers I would suppose.

Can you proivde link to videos or sound records to illustrate the question? I cannot remember the sound of the undercarriage the last time I took a plane.

@ManuH The Fokker's undercarriage sounds like a giant sprint being released.
In fact it's not the only interesting noise it makes; when the engines are idling after a flight, they rattle like a huge metal box full of screwdrivers being shaken (I guess it's the slightly loose turbine blades). Sometimes passengers disembarking seem a bit startled when they realise where the racket's coming from.

Without hearing it I would imagine that what you are hearing is the landing gear reaching full extension and hitting it's mechanical limit. Think of it like one of those bicycle air pumps, and the sound it would make if you pull that handle all he way up. It's the same basic mechanism, except upside down, and the landing gear should be full of hydrolic fluid to support the force of the aircraft landing on it.
One aircraft has a mechanism that has a hard stop at the end of the stroke, and so you hear the extra forces being translated as that sound. The other aircraft has a softer end, so maybe there is a spring or rubber bumper pice or something that softens the end of the extension.

What is actually used is a pin of varying diameter inside the damper, so the resistance against movement (= damping) can be tailored along the stroke. I would expect the more modern aircraft uses this to decelerate the oleo strut extension near the maximum stroke.


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How should we think of 'layers' of air flow?
Do a search for "boundary layer" or "laminar flow" on this site, and you'll find plenty of things to read.
They'll talk about "the boundary layer", "flow separation" and so on, as though it were completely obvious what they actually were. Sometimes, they'll even be illustrated with diagrams representing the strata in the flow of air.
I'm no physicist, and this talk and these diagrams make me imagine the fluid equivalent of plywood, or expensive paper handkerchiefs, constructed of discrete layers of material that can be readily identified as such and peeled away from each other.
Is that really how these layers of moving air work? Is the boundary layer over an aircraft's wing like a discrete sheet, with a clear and distinct boundary between the next discrete layer? Or is there a smooth continuum, rather than a distinct step, between the layers and their properties?
Do distinct layers exist more in the conceptual analysis of aerodynamic behaviour than they do in readily identifiable physical entities?
If you were to plot a graph representing some property of the air flow (say its velocity, direction, pressure or turbulence) against distance from the surface of the wing, what sort of shape would the curve have?
In short: how should we imagine these layers?

Very useful question imho. Not an answer, but may help: Streamlines depict arbitrary lines or surfaces were the velocity vector is tangential to it (not necessarily the path of a fluid molecule). In a plane normal to the flow direction, viscosity and density variations make changes in velocity and pressure progressive as long as the flow is laminar. The boundary layer is the volume where the speed transitions from 0 to the overall velocity around the airfoil due to viscosity.

Please ask about the speed distribution in a separate question. Both speed and thermal boundary layers can assume all kinds of weird shapes, depending on the pressure gradient and thermal energy flows.

To understand what a boundary layer is think about air moving above a flat plate. Before the plate and very far from it the air has everywhere the same speed and direction. However, directly on the plate its speed is zero: molecules directly on the plate do not move at all.
Between the plate surface where the air isn't moving and some distance from it where the air has a constant speed, there is a zone where the air changes its speed a lot. We call this zone boundary layer.
There isn't really any clear and distinct boundary delimiting it. That's why we have many definitions for its thickness. The dashed line in the image below is probably the 99% boundary layer thickness.

Generally we give a name to a layer when the physical effects and properties of the fluid in this concrete zone can be differentiated from the rest of the flow. Most of them are on fluid boundaries (body surfaces, places were fluids get gaseous,...) but you can have them inside a fluid too (shock waves).
For example, instead of looking at the velocity you could look at the temperature of a fluid flowing around a very hot body and define a temperature boundary layer.
Some known layers are:

Laminar boundary layer
Turbulent boundary layer
Blasius boundary layer
Stokes boundary layer
Ekman layer
Shock layer
Knudsen layer
Merged layer

Temperature boundary layer

For me the best comparison is with a multi-lane road. Imagine you drive along and all drivers stay in their lane. Then it will be possible that all the cars in one lane zip ahead while another lane crawls along.
Now imagine that drivers switch lanes frequently. The slow ones changing into a fast lane will force the others to brake, while the fast ones cutting into a slow lane will push the laggards forward.
Drivers who stay in their lane are like air molecules in a laminar flow. They follow a straight path and interact with their neighbors to the left and right mainly through shear, which will change their speed only slowly. On the other hand, air molecules in turbulent flow wiggle around all the time and bump into slower molecules, or get bumped by faster ones. This makes all of them assume the same speed, more or less. Only at the wall you find a strong speed gradient, maybe like at an onramp on a highway. The slow cars entering the highway speed up really fast when others will cut into their lane frequently.
Of course there are no lanes and no lane markings in air. Airflow is like a highway with an infinite number of infinitesimally small lanes, and instead of producing accidents, molecules which bump into each other are merely creating local pressure. The boundary layer which is mentioned so often is in the end a matter of definition: The boundary layer is defined to end when the local flow has reached 99% of the flow speed outside of the boundary layer. This allows to split the flow into a regime without viscous effects far from the body, which is easier to calculate, and one with viscous effects in a thin sheet around it. In reality there is no such thing, all air follows the same laws.

Think of the layers more as a liquid - imagine running water, just as there is sometimes a fast moving flow of water on the surface or in a reduced space, with slower moving currents beneath the surface.
Aerodynamics is actually an area of Fluid Dynamics, with air being a compressible fluid.
The Navier-Stokes equation can be derived to show mathmatically how the boundary layer actually works if you wish to invesigate further.

@andrea This doesn't really help - exactly the same questions then apply to how layers function in water - how discrete are they; what sorts of continua exist, and so on.


text:
What are some design choices to give an aircraft faster cruise speeds vs flying an already efficient aircraft at a fast speed?
I want to design a UAV to fly at faster cruise speeds than usual. Setting aside the powertrain selection, which will probably be a big part of this, I want to know what kind of design choices I can make that would make this aircraft more efficient at faster speeds, vs designing a traditionally efficient aircraft (Fly it wherever the L/D is the highest) and flying it faster.
From what i understand, wherever the max CL/CD is at is the most efficient aoa/speed to fly at. How would we design an aircraft to solve max cl/cd for a certain speed? i.e., if i wanted to design an aircraft to cruise and be its most efficient at, say, 130mph instead of 60mph. Is there design choices that'd make it more efficient at those speeds (Low lift airfoils, picking airfoils for the right RE numbers, etc), or is this as simple as making an aircraft with a high CL/CD and making it fly at faster speeds?

Are you asking how to generally increase L/D or how to set the wing such that at 130mph it is at its highest L/D?

@sophit yeah basically how to set the wing such that 130mph is the highest L/D

Understand. Anyway I was thinking that the point where L/D is max isn't actually related to the max speed rather it is the condition maximising loiter for a jet and range for a propeller or a glider.

Look to purpose built F1 racing airplanes for your answer. Basically, smallest possible frontal area, overall cleanliness, and small wings. If you want to go at multiples of best L/D speed, you need to raise the wing loading by making the wings small (and obviously, optimizing airfoil selection and such).
Problem then is high landing speeds. If you can't live with the resulting landing/takeoff speeds with itty bitty wings, the workaround for that is high lift devices that deploy from the little wings to reduce the landing speeds.
So an optimized design would have the smallest cross section possible, careful attention to parasite drag, cooling drag etc, and small wings, offset by, say, double slotted full span flaps and possibly leading edge slats to raise the max L/D of the wing you have in the takeoff/landing configuration, enough to compensate for the lack of wing area.
Of course, the high lift devices add a lot of weight, which might force you to make the wings bigger anyway, which add more weight again, and off on the design merry-go-round you go.

I see. I'm trying to have as much range as i could get as well. Would I follow this philosophy and try to squeeze as much L/D out as i could as well, and just spin around the design merry-go-round until i arrive somewhere favourable?

There's so many variables. If you create a large fuselage tank for all the fuel, you have to account for spar bending from the fuel load. If you put the fuel in the wings and, say, external tip tanks, you save weight in the wing spar but it costs you speed. If you want extreme range, you will probably be forced to use some form of wing mounted underslung or tip mounted tanks. If you have an engine decided in advance, and you have a range/speed target, you design around those objectives.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
In the ARINC specification, why is baro altitude (label 204) measured in Knots?
I am currently designing a system that reads the baro altitude (on label 204) from an LRU. Ultimately in my software I would like to display the baro altitude reading in real-time using a graphical interface. In doing this, I'd like to have the units of measurement next to the reading. However I am having a bit of trouble in deciding how to display the units of measurement.
In the ARINC specification (attachment 2 "data standards"), label 204 (baro altitude) is listed as having units of knots. Is this an error, or can altitude be in Knots?
I am referencing ARINC specification 429 part 1-17, mark 33 digital information transfer system (DITS) published in May of 2004.

It's an error. Attachment 2B does show that label 204 from the GNLU (Equip ID 056) and GLU (Equip ID 060) as being in knots (highlighted below). That is not correct, it is a BNR in feet as shown for Air Data System (ID 006) and ADIRU (ID 038). Knots only applies to Label 204 from the FMS (ID 002).

It's still incorrect in A429 P1-18, March 2012.
ARINC 429 contact at ARINC Industry Activities, ARINC 429 Maintenance is Jose Godoy. email:jose.godoy@sae-itc.org

Nice!! Thanks for this, guess we'll need an updated spec.

@ Gerry, @Snoop, Label 204 might refer to an airspeed as well to an altitude it depends on the emitting equipment, please read my answer to understand the matter.

@user40476  While you are correct in your statement, it's irrelevant to the original question which asked why the Label 204 Baro Altitude outputs from the GNLU and GLU was defined in Knots instead of Feet.  I've edited the answer to make the point clearer.

Please read all the explanation to understand how the same label might refer to different parameters, therefore to different units.
As a start the label uses only 8 bits which gives a space for only 256 different labels ( 377 labels in octal base), this is obviously insufficient to cover a huge number of parameters of a modern aircraft.
To increase the number of possible parameters, and to cover the complexity of modern systems, the same label according to the emitting computer might refer to a different parameter; more precisely, different equipments might use the same label to send different parameters even though using the same label.
Please refer to the following Website
http://read.pudn.com/downloads111/ebook/462196/429P1-17_Errata1.pdf
You will find that depending on the emitting equipment the same label might refer to : utility airspeed, or baro corrected altitude, or duct temperature, etc etc therefore the units will depend on the equipment that transmits the label.
Label 204 could be send by the flight management, or by the air data computer, or by the fuel and quantity computer, etc, etc.
As a conclusion the same octal label do not refer always to the same parameter.
Is this confusing?
No because a sink computer knows on which bus he is reading and therefore knows the equipment that is sending the data.

It isn't an equipment ID or label decoding issue, the A429 standard does in fact have an error for Baro Altitude on equipment IDs 056 and 060. I expect it is a copy paste error from the 002 Utility Airspeed entry, as the table data is the same. I'm assuming that the equipment ID the OP is either 056 or 060 for this to be an issue.

@selectstriker2, please refer to the website I mentioned, and have a look at label 204, then you will understand that label 204 when emitted by the fuel system necessarily has different unit than when emitted by the Air Data, or by the flight management etc, because it concern different parameters eve though having the same label. So label 204 could be in knots or in feet or in pounds, it is your job to use the proper unit as a function of the equipment IDentifier

I understand that, but that isn't what this question is about. The OP is getting label 204 from a transmitter with the equipment ID of either 056 or 060, and the entries in ARINC 429 for those IDs and label 204 are incorrect.


text:
In the ARINC specification, does "sig bits" include the sign bit?
In the ARINC specification, there are sections where all of the different labels (and their pay-loads) are described. In each of the tables where the labels are defined, there is a column called sig bits. For where the labels are designated as BNR, do the sig bits include the sign bit?

What is missing in the Wikipedia article? For BNR, the sign bit is bit 29 of the word.

Wikipedia's table for sign bit is the exact copy of the original table found in §2.1.5.2 BNR Numeric Data Words of ARINC 429 documentation.

In A429 BNR words bit 29 is the sign bit.  Individual label descriptions are not entirely consistent in that many will identify bit 29 as part of the sig bits field.
In any case it's important to look at the details of a specific label, especially the range, MSB, and LSB values.  Some are always positive (such as airspeed) and so the sign bit is assumed to be positive and bit 29 can be the MSB.
One common factor is that the majority of BNR labels are coded in 2's-complement binary.  In this case, the MSB is half the range and each of the following bits is half the value of the previous. Example: For a "heading" range of 0 to 359, the MSB (bit 29) is 180, the next is 90, followed by 45, 22.5, 11.25, etc. Alternately, you can declare bit 29 the sign bit and the range becomes -180 to +179.
So you'll note that in 2's-complement encoding, it doesn't matter if you consider bit 29 as an MSB or a sign bit.  The difference is that if you call it MSB, the range is 0 to 359.  If you call it a sign bit, the range is -180 to +179.
You can prove this to yourself by declaring bit 29 as a sign bit and code -135 degrees.  Then declare bit 29 a MSB value of 180 and code 225 degrees. The coding should be the same.

I believe this explanation is valid for angular data (which is a special case described by the comment in § 2.1.6 of the standard), but not for linear data where the LSB is made equal to the resolution.


text:
Advice for a future pilot?
I've always wanted to be a pilot from the age of 3. I've always dreamed about flying high in the sky above the clouds and getting that amazing experience that you can't get any other way.
I'm now turning 16 and am realising it is coming close for me to start my goal of becoming a pilot.
I would appreciate if anyone could give me some advice on what to do to become a pilot.
What qualifications you need?
Where you train?
Wages?
What are the health requirements?
Etc
This is for a pilot in the UK who is hoping to work in Dubai for Emirates.
Thanks.

Typically to get to work for an airline like Emirates, you are going to have to put in many years of experience at smaller regional airlines and work your way up into the "major leagues". Some companies like Emirates have very high entrance standards so make sure you stay educated, out of trouble, and proficient throughout the journey to that company. Try to connect with an Emirates pilot and find out how they got to where they are.

There's only one place I can think of that will take an untrained person and teach them to fly and pay them for it rather than the other way around: the military.

What you could do right now is train to be a glider pilot. You probably already have the right age. It is a wonderful experience, and it will be a good basis for a power license.

What I hear from other pilots I know is that learning to glide actually makes you a much better powered pilot as it teaches you the importance of coordinated flight and using your feet whereas it's easy to be sloppy with your feet if you've never done it before. Good footwork is important in flying. Also, gliding will give you great experience in judging the flight envelope of any airplane... In gliding you learn to make the best and most efficient use of the only energy source you have - altitude and gravity (okay, thermals, but yeah). I plan on learning to glide one of these years soon.

Remember that the great majority of pilots don't get paid to fly, we pay to fly - for lessons, renting or buying a plane, fuel, etc.  There's a big difference between the effort, qualifications, and money needed to become a private pilot, and what's needed to become a comercial or airline pilot.  In the US, at least, anyone in reasonably good health can become a sport or private pilot.
I hope I'm not offending anyone here when I say that being a commercial pilot is work, and making just about anything into an 8-5 job can take the edge off that amazing experience.  Or at least it seems that way to this private pilot :-)


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What might a pilot mean by "uncontrollable"?
The air safety reports from FlyDubai aircrew leaked to the Guardian contain some alarming stories about crew rostering, tiredness and duty times, but another one caught my eye, a description of an encounter with severe clear air turbulence on a flight from Moscow to Dubai (search for 511 VKO-DXB):

Aircraft was uncontrollable at time for 10-15 seconds every now and then. Total duration probably around one and half minute.

What does the pilot mean by uncontrollable? That the aircraft wasn't responding to commands and the crew were helpless passengers, at the mercy of the weather, and that everyone survived simply because it didn't go on long enough to tumble the plane out of the sky? Or that it was just being a bit difficult?

I means exactly what is written, the crew was not able to control the aircraft attitude, altitude and speed due to the turbulence. The aircraft was close to the maximum Mach number for operation (MMO). At cruise altitude (low air density), the difficulty is to remain in the small range of speed allowed (between MMO and stall) materialized in the speed indicator between the red and amber bands.

If someone asks "What is meant by 'controllable' in this context?", "It means exactly what it says" is not really a good answer, unless you want to imply that the person who asked it was too stupid or too lazy to work it out for themselves. I'm not lazy or stupid, and it's not completely clear to me what a pilot might mean by those words in that kind of report.

You might be interested in the AIM section 7-1-22, which gives guidelines for reporting turbulence. The ones for severe turbulence say "Occupants are forced violently against seat belts or shoulder straps. Unsecured objects are tossed about. Food Service and walking are impossible." That might give you some idea about the actual experience, if that's what you're looking for.

@DanieleProcida: "[this] is not really a good answer". This is not an answer, but a constructive comment. I don't have any reason to suggest what you imagined, your question is legitimate to me.

@Pondlife That is indeed interesting ("Eyeballs bounce so hard in their sockets that it causes bruising") but it's not an account of the experience that interests me here. I want to know what it means for the pilot to have lost control. If I lose control of my bicycle for 10-15 seconds, I'll be upside-down in a ditch. Or in my car, I'd expect to be giving my post-incident report from a hospital ward, or in front of a judge. In either case, loss of control implies loss of safety.

@DanieleProcida the difference is your bike and car are already on the ground.  At FL370 (37,000 ft) you generally have a long way to fall till you hit anything hard.

@NigelHarper Of course, but just as on a bike or in a car you can find yourself in a condition from which you will never recover control, the same can happen in an aircraft. Having longer to go before you run out of road or sky will help if the condition is recoverable but it's no guarantee; if the condition is unrecoverable, it's not going to help at all.

Of course, but "uncontrollable" by itself doesn't imply unrecoverable; it simply talking about the current situation.  A car in a skid and an aeroplane in heavy turbulence may be uncontrollable in the moment but may be recoverable without serious incident.  Or they may not.
The fact that you have more latitude in an aircraft means that longer periods of loss of control are more likely to be recoverable than in a ground vehicle.

"Uncontrollable" is a technical term (actually, in literature it's more often called "loss of control"). It means the aircraft is not responding to at least one normal command. Be it elevator or ailerons or rudder etc.
Really, really good AND lucky pilots can sometimes still control aircraft that's uncontrollable. Either by using another control surface to influence the control desired (eg. by using rudder to get out of a bank) or by using non-primary surfaces like trim tabs or flaps.
When no control input will influence what the aircraft is doing then it's called total loss of control (or totally uncontrollable).

Note that even total loss of control is not in and of itself catastrophic.  An airplane is normally balanced so that it'll fly straight and level in the absence of control inputs, so you may have several hours for troubleshooting before things become critical.


text:
How do large airport refuelling systems work?
As I am sitting on board my plane and have been informed that there may be a three-hour delay due to a pressure problem in the fuelling system at the destination, it seems like an appropriate moment to ask: how do these systems at large airports (in this case, Amsterdam Schiphol) work?
Apparently, it is an airport-wide problem affecting all flights that need refuelling.

How and where is fuel stored?
How is it delivered to the aircraft?
What sort of technical problem with pressure could affect an entire airport the size of Schiphol?

Amazingly enough, fuel is delivered to Schiphol, Brussels or Frankfurt via the CEPS, an old 5,000 km NATO pipeline connected to ports all over Europe.

@mins: And  weird: DUS, Germany's  3rd largest airport after FRA and MUC, gets its fuel delivered by about 120 trucks a day... And this, though the airport has two train stations, and tracks to the fuel tanks. They are going to switch to train about now...

At Frankfurt/Main airport there is no fuel carried over the airfield to (larger) aircrafts.
There is a pipeline system in the  floor and the Trucks only carry a pump and a hose to connect the plane with the fuel pipeline.
Maybe your target airport has a similar fuel distribution system that failed somehow...

Amsterdam indeed has just that, and a few small trucks to service places like the GA ramp and the police helicopter ramp where the aircraft don't tend to have standardised connectors for the high pressure fuel systems used by airliners.

For Amsterdam, fuel is stored in several large above ground tanks (which can be seen from quite a distance away) and maybe some underground tanks as well.
From there it is pumped into a system of underground pipes to the refueling pits at the aircraft parking spots around the terminal (and to points from where fuel trucks can be reloaded).
Fuel is thus (depending on the location where the aircraft is parked) loaded either through fuel trucks or using hoses hooked up between the aircraft and the fuel pits (there are special trucks for this containing the connectors and control systems, delivery counters, etc.).
What could affect the entire airport? Blockage at a few key points, failure to get tankers in to replenish the supply, several vital pumps failing together.
More likely it was a localised problem at your ramp, but due to heavy traffic no fuel trucks were available to refuel you by trucking in fuel from elsewhere on the airport.

"More likely it was a localised problem at your ramp" No, because the asker was told that the fueling system had failed at his destination airport, not at the departure airport.

@DavidRicherby misread that, seems weird though that a departure is delayed due to a problem with a fuel truck at the destination (unless the destination is somewhere far away from anywhere and you couldn't divert to get fuel on the trip back if things went ape).

@jwenting --- they'd have to redo a bunch of numbers back @ dispatch as they'd then be tankering fuel for at least one leg

As indicated in the question, the issue was at the destination airport, and was a pressure problem affecting all of Schiphol. We were informed that landing slots were unavailable because space for parking had run out.


text:
How long has the term "situational awareness" been used in aviation?
I was puzzled to read (Wikipedia article on situational awareness) that:

The term can be traced to World War I, where it was recognized as a crucial skill for crews in military aircraft.

but in the next paragraph:

There is evidence that the term Situational Awareness was first employed at the Douglas Aircraft Company during Human Factors Engineering research while developing vertical and horizontal situation displays and evaluating digital-control placement for the next generation of commercial aircraft.

and then the next:

Situation awareness appears in the technical literature as early as 1983

I imagine that the concept found work in understanding piloting very early on; what is the history of the term in aviation?

You could try english.SE if you don't get a useful answer here; they have lots of questions about the history of words and phrases.

Not definitive, but I recall the use of that term with an instructor when I was getting an instrument rating in the 70's.

What a great question.  I would love to know the answer to this.  I wasn't aware that the term specifically arose from aviation; awesome.

@Fattie I am not sure that it did - I think that aviation may have taken it (the term) from military usage.

FWIW, the earliest reference that Google Ngrams can find is in 1946. It may have been used before that, of course; I have no idea how extensive/reliable Google's corpus is.

According to M. Press, in his 1986 unpublished manuscript Situation Awareness, let's get serious about the clue-bird which is cited by many authors, the concept of SA can be traced back to aces of WW1, in particular Oswald Boelcke.
According to M. Press, his success was due to him being aware of the enemy before the enemy sees him.
From Situation Awareness Analysis and Measurement, Mica R. Endsley, Daniel J. Garland, p7:

The earliest discussions of SA undoubtedly derive from the pilot
  community going back as far as World War I (Press, 1986)

The word "Lage" has been used in the Prussian military at least since von Clausewitz to describe the military situation. "Luftlage" was then a logical extension when officers started to fly planes.


text:
Do the A380 ailerons act as air brakes on landing?
Last month I was on an Emirates A380 to London Heathrow. I noticed on the landing, the right ailerons were fully up along with the spoilers when decelerating on the ground. Are the ailerons configured for acting as air brakes on landings? Or was the pilot perhaps counteracting a crosswind?

Yes the ailerons deflect upwards after main wheel touchdown to dump as much lift as possible: they work as lift dumpers, together with the spoilers which are deployed first.

Source: an A380 pilot plus the FCOM.
Update
Just arrived on an A320, from could see both ailerons and they both deflect upwards as well after touchdown.

Do you still have roll control on the ground? Or, related, wouldn't a strong crosswind tend to lift the upwind wing?

Roll control on the ground is done by the landing gear:). It's important to let the tyres do their job as fast as possible to avoid skidding.

The ailerons, along with the spoilers are configured to act as lift dumpers on touchdown in most of the newer Airbus aircraft. This was introduced in the Elevator Aileron Computer ELAC standard L96, where,

Aileron up deflection at ground spoiler extension becomes basic function.


text:
Is it normal practice to refuel commerical planes whilst boarding is taking place?
The other day, I was on a KLM Boeing 737. I had just sat down in my seat, and the captain was making announcement. He said something along the lines of,

As we are refuelling at this moment, please take your seat quickly, leaving your seat belt open, and follow any instructions by the cabin crew immediately

This suggests to me that refuelling whilst boarding is not normal, as I've never heard this before, and it sounds like they want us to be ready to evacuate if something goes wrong with the refuelling.

Related: Under what conditions are passengers required to take precautionary measures during refueling?

Refueling with passengers onboard is quite normal and is done according to the recommendations of regulatory bodies/manufacturers and operators. Refueling with some fuel types are not permitted, while others are. From Airbus Flight Operations Briefing notes:

Refueling  with  wide  cut  gasoline  type  fuel (JET  B,  JP4  or  equivalent)  or  when  a  mixture  with  these  types  of  fuel  might  occur,  is  not  permitted  with  passengers  boarding, on board or disembarking.
Refueling with Kerosene (JET A, JET A1 JP8, TS1, RT, TH or equivalent, as approved by  the  approved  Aircraft  Flight  Manual),  is  allowed  when  passengers  are  boarding,  on board, or disembarking.

Some precautions are required to be followed in case refueling is done with passengers on board. The announcement you heard is simply following that. From Appendix 1 to JAR-OPS 1.305 Refuelling/defuelling with passengers
embarking, on board or disembarking:

(a)   An  operator  must  establish  operational procedures   for   e/defuelling   with   passengers embarking,  on  board  or  disembarking  o  ensure  the following precautions are taken:
(1)   One qualified person must remain at a specified location during fuelling operations with passengers  n  board.  This  qualified  person  must be  capable  of  handling  emergency  procedures concerning  fire  protection  and  fire-fighting, handling  communications  and  initiating  and directing an evacuation;
(2) A  two-way  communication  shall  be established  and  shall  remain  available  by  the aeroplane’s  inter-communication  system  or  other suitable   means   between   the   ground   crew supervising  the  refuelling  and  the  qualified personnel on board the aeroplane;
(3)  Crew,  staff  and  passengers  must  be warned that re/defuelling will take place;
(4)  Fasten eat Belts’ signs must be off;
(5)  ‘NO  SMOKING’  signs  must  be  on, together   with   interior   lighting   to   enable emergency exits to be identified;
(6)  Passengers  must  be  instructed  to unfasten  their  seat  belts  and  refrain  from smoking;
(7)  Sufficient qualified personnel must e on  board  and  be  prepared  for  an  immediate emergency evacuation;
(8)  If  the  presence  of  fuel  vapour  is detected inside the aeroplane, or any other hazard arises  during  re/defuelling,  fuelling  must  be stopped immediately;
(9)  The  ground  area  beneath  the  exits intended  or  emergency  evacuation  and  slide deployment areas must be kept clear; and
(10) Provision is made for a safe and rapid evacuation.

You're right about the announcement and leaving seat belt open- it is to help in quick evacuation. The flight crew is just following the procedure.

Some airlines also require passengers to keep their shoes on.

It's very common on Ryanair flights. Any time the plane spends on the ground is a cost, and anything that reduces this will reduce the airlines costs.


text:
Why would Emirates fly over Iraq, avoiding Iran?
For the last few years flying with Emirates from the UK to Dubai, I've noticed it avoids Iraq and fly over Iran to the north. For example, EK40 from BHX to DXB

From Flightradar24
However, flying this month on EK40 I noticed the exact opposite, the flight avoided Iran and flew over Iraq to the south.

I know that the conflict in Iraq has mellowed recently, but that doesn't explain this: the first picture is of EK40 on Feb 7th 2018, while the second picture is of EK40 on Feb 6th 2018.
So, what could be the reason for avoiding Iran so explicitly when the next day the same flight avoids Iraq?
EK 040 on Flightradar24

Since December 2017 the Iraqi airspace is used by Emirates again, after Iraq declared the victory over the Islamic State.
Now there are basically two routes to choose between when flying from Turkey to Dubai.
One route passes through Iran  and make it look like the flight is explicitly avoiding Iraq. The route crosses the Ankara FIR / Tehran FIR border just north of Iraq, before turning south towards Dubai, such that it just stays outside Iraqi airspace.
The other route (UM688) passes through Iraq and makes it look like the flight is explicitly avoiding Iran. The route structure in Iraq is such that the north-south routes follow the Iran border in order to avoid the military activities near the Syrian border.
The map below shows the route structure with two routes through Iraq highlighted (UM688, Southbound and UM860, Northbound).

source: Flight Service Bureau
It is likely that the choice of route is made based on financial reasons. From looking at recent flights, Emirates seems to have a preference for flying over Iraq, but occasionally flies over Iran.
The ATS overflight fees of Iraq are at \$3751 (approx. \$0.38 per km) considerably cheaper than those of Iran. Iran charges \$0.004061 per 1000 kg Maximum Take-off Mass (MTOM), per KM, with a 30% reduction for the MTOM in excess of 150 000 kg. For an A380, the cost of crossing Iran would be approximately \$2800 (approx. \$1.80 per km). The slightly longer flight over Iraq, Kuwait (~\$1351 ATS fees) and Bahrain (~\$2101 ATS fees) would consume more fuel but will still be cheaper than crossing Iran.
A reason for crossing Iran occasionally might be that Iraq's airspace is very congested since the re-opening of the airspace. To avoid delays, sub-optimal altitudes or adverse meteorological conditions it may be more attractive to cross over Iran in certain situations.

1sources of the ATS Fees: AIP's of the respective states, section GEN 4.2. As high volume users, Emirates may have negotiated better rates.

Relations between Iran and most of the Gulf countries have been strained for a few years. The main issues revolve around Iran not willing to join in the gulf oil-pricing strategies. This dates back to the late 70s and was one of the reasons the Shah of Iran was removed as he was seen to be putting OPEC and US interests ahead of Iranian. When Saddam invaded Iran in 1980 it was with the tacit approval of Saudi Arabia and the rest of the gulf states.
Aviationwise,  a few months back most of the gulf states closed their airspace to Qatar Airlines because Qatar was deemed to be too friendly to Iran. The UAE was one of those who closed their airspace to Qatar and I would imagine this would have soured the relationship with Iran as well. Based on this, I imagine Iraq would seem a friendlier place to overfly!

I think you mean "when Saddam invaded Iran"

ooops..fixed it! Thanks binaryfunt!


text:
What is the cause of this roll oscillation during BA492 go-around?
Earlier today, BA492 aborted a landing at Gibraltar due to a strong tailwind, according to this article. Videos of the go-around show the Airbus A320 undergoing pronounced oscillation in the roll axis:
[Content warning: both videos contain profanities]

What is the cause of such large magnitude oscillations?

The flaps seem partially extended, would that have any effect?

It was 'normal' operation - southerly winds create rotors coming off th Rock. This was warned to all aircraft when these wind conditions exist.  The flight crew executed a go around and proceeded to Malaga.

This video by Mentour Pilot explains what happened.


text:
What skills do aviators have uniquely that could cross over to another industry?
I have developed sensitivities to several chemicals used in aerospace. I have to make a shift away from our industry, so I would like to know what are qualities in aviators that would be unique and set us apart from other candidates in a good way. One that immediately comes to mind is our respect for inherent risk. What other tacit knowledge or soft skills apply?

Are you asking specifically about pilots? What kind of pilots? "Our industry" covers a lot of professions and a lot of variety within those professions.

Any aircrew would suffice.

I'm just asking but, have you thought about teaching PPL/ATPL? It's obviously not the same income as a pilot (usually), but you still keep in 'our industry' which I'm sure you really like the most.
Sorry about those sensitivities...


text:
In what direction(s) is any debris typically ejected from a jet engine in the case of failure during flight?
Has there been evidence of ejected material striking the fuselage or other parts of an aircraft forward of the engine itself?
Which of the various forces acting on rotor blades dominates the trajectory of pieces in the case of a blade failure?
Other than rotor break-up, what kinds of engine malfunction typically cause component separation, and in what direction(s) is material ejected?

There are many studies on the topic of uncontained engine failure. e.g.: Large Engine Uncontained Debris Analysis, or Uncontained Engine Debris Analysis Using the Uncontained Engine Debris Damage Assessment Model,  and Uncontained Engine Failure.

There is one crash I can think of, where the engine itself separated, traveled forward and struck the leading edge of the wing. This was American Air Flight 191.

QF32 had an uncontained engine failure in which debris went in multiple directions, but by pure luck avoided the fuselage.

Technically speaking, AA191 was not an engine failure. It was a pylon fuse pin failure due to faulty maintenance techniques, leading to partial and then total separation of the pylon with engine attached. The engine was working just fine when it pivoted upward and then over the wing due to pylon separation, tearing out the leading edge flap.

For debris ejection out of the engine, the failure of the engine and the failures that follow that create debris; the design criteria is that the failures must be contained in the cowling and the debris exits through the exhaust. Here is the link to the FAA Advisory Circular for designing for catastrophic failure: AC 20-128A
Here is another link that is more devoted to prior uncontained engine failure.

Debris should be contained (and there is a check for this to certify the engine). However they are not always, so the accidents, I think the question is about the latter cases, not what is expected (to some extent).

When the fan disk failed during UA232, there was damage forward of the fan disk itself.  See also the associated damage image.  While this was not forward of the engine nacelle, it seems to address the intent of the question.


text:
What are the most significant risks to life for the airline passenger?
Suppose that I start taking long-distance airline flights, and that after each flight I immediately jump on to another aircraft that takes off for another faraway destination - and continue doing this, indefinitely.
In other words, I'm going to live the rest of my life travelling on airliners.
What's going to kill me first:

an airline accident or incident
excessive radiation exposure
some other flying-related health risk
old age?

If the answer is old age, then let's suppose for the sake of the question that I'm also going to live indefinitely, until one of the other factors does me in.
Exclusions
I'm only interested in risks that are specific to flying. I suspect that breaking my neck falling down the steps or choking to death on an in-flight peanut might be higher, but they don't count, because I use stairs and eat peanuts regularly anyway.
I guess exposure to infectious diseases (and other risks associated with the airline cabin environment) should count, since air travel does  increase those significantly.
The health risks of an airline food diet are excluded though, especially if I decide to fly economy class. So is dying of despair.
However, the risk of severe food poisoning should be included.
Finally, I'm only flying on scheduled flights on reputable airlines.
The comparison
As you can probably gather, the device of the hypothetical permanent travel  is simply a way of framing the risks for the sake of comparison. I'm not really interested in what it might be like to fly forever, but in the quantum of risks in airline travel.
On the other hand there presumably come a point where the frequency of travel means that some risks become disproportionately more significant (e.g. eating 70 airline meals a year might be simply unpleasant, but eating 700 would be to suffer from a genuinely unhealthy diet).
However I can't think of any risks of that kind that would start to increase at a rate greater than frequency of flying, within any normal flying frequencies.
Future risk changes
I assume that flying is going to continue to become ever-safer, which could mean that the risk of an incident or accident will fall over time while (say) health risks don't. For the sake of a fair comparison, let's say that even into the far future the risks will remain as they are today.

I think this is probably opinion based since I doubt that there are stats to support an answer to this entirely hypothetical question.  The answer is old age but since you have discounted that, radiation exposure is probably the next which I would expect to get you after a few hundred years.  You'd have to fly for tens of thousands of years before being involved in a crash.

The trip to the airport.

@Simon opinion-based? You mean the last 100+ years of commercial aviation has failed to accumulate and analyse statistical data about risk? All the data to calculate these risks already exist. Or do you imagine that flight risks, radiation exposure risks, life expectancy and others are a matter of opinion? The question is eminently answerable using those data as a basis.

@DanieleProcida The risks are so small that there is no statistically accurate way to answer your question.

@J.Hougaard The risks are quantifiable, and an area of active research. http://hps.org/publicinformation/ate/faqs/commercialflights.html, just for the example of radiation exposure.

If you remove the "live forever" bit, then yes, they are answerable, and "old age" would win by a long way making all other risks insignificant.  But you have constrained the question such that the statistics are so small (tiny, tiny percentages in millions of flights), that the question becomes unanswerable.

Heh, I see the maniacs for closing questions are out in force again today.

The rudeness is unwelcome.  "Or do you imagine that flight risks, radiation exposure risks, life expectancy and others are a matter of opinion?".  You removed life expectancy.  The "flight risks" are not statistically significant and radiation exposure is a strong candidate but how, given that you have constrained the definitive answer, could you possibly measure that against food poisoning, infectious diseases and other random events?

I don't think the question is unanswerable, even with no age limit, though answering might require expertise in health domain that might be lacking here. A factor may create a risk which becomes effective only when added to other risks (like it might be for cancer, for instance), this makes the answer more difficult.

I find it pretty rude to dismiss carefully-constructed questions with what seem to be unthinking or even unreading reactions, of the kind that this forum sees all-too-often. Of course these risks are tiny. But there is an entire industry devoted to very small but quantifiable risks, that uses vast longitudinal and large-cohort data to compare them, and is able to state: "percentage risk of falling victim to risk A in X years is Y; of risk B, it's Z" etc. These are not just matters of opinion.

@DanieleProcida I agree with your last comment about very small but quantifiable risks not being a matter of opinion.  However, that may make this more of a statistics question or an insurance underwriting type question and you may not find an appropriate expert here on this site.  The experts here tend to have a different type of expertise in the aviation arena.  Good luck, you never know who might run across this question and have the perfect background to answer though!

I agree with @mins. It is an answerable question but it is probably best done in a thesis, rather than an internet forum. So unless someone has already done one you're unlikely to get an adequate answer here - but is that reason enough to close the question?

@Ben: Correct, this is not a valid reason, someone may be able to answer one day this interesting question.

I think stroke, cancer, and heart attacks or something?  Car crashes is also somewhere on the list?

I'm voting to repoen. It is a well constructed question indeed, and an internet meeting place like this is exactly where you may run into someone with apliccable  knowledge. I really do not understand why we have very vocal people here who see it as their task to censor everything outside of their own personal knowledge.

Reducto absurdum can be a fun game to play, but what you have set up is an unrealistic premise; you are idea farming, which is why "opinion based" is what your question remains.  -1.   (And you'd probably die of boredom first ... )

Boredom comes to mind...............

Risks of dying of air travel are tiny. We can find data on direct risks of air travel, and there is an app for calculating how many years of continuous flying would lead to known aviation related chance of dying. Tiny.

Some risks ore harder to quantify though. If you fly economy class, you may be exposing yourself to the health risk of excessive sitting. It damages blood vessels and may lead to Deep Vein Thrombosis which can cause sudden death. From this news article of 23 Oct 2000:

Emma Christoffersen, 28, died from deep vein thrombosis (DVT) believed
  to have been caused by sitting for several hours on the 12,000-mile
  flight to Heathrow from Sydney. Medical experts said she was one of
  the youngest victims of DVT, a sudden illness caused by lack of
  movement over a sustained period that claims the lives of a number of
  airline passengers each year.

Also, you're excluding the effects of airline food. An economy class meal costs between USD 2.- and 10.-, how good is that for someone to eat day in day out?
Air travel is not an activity that is good for health if undertaken on a daily basis. During a long economy class flight people should get up for a brief stroll every few hours or so, and once landed should be vigorously walking around in the sunshine over the course of a couple of days to reset their blood flow and health before taking another flight. Like pilots do.
From Mayoclinic.org:

One study compared adults who spent less than two hours a day in front
  of the TV or other screen-based entertainment with those who logged
  more than four hours a day of recreational screen time. Those with
  greater screen time had:

A nearly 50 percent increased risk of death from any cause
About a 125 percent increased risk of events associated with cardiovascular disease, such as chest pain (angina) or heart attack

Air travel is very safe and mortality rates are low, as illustrated in this article from The Economist. It is a good thing though that most of us only take a couple of flights a year, with ample time in between flights. But it's not only economy class travel that is bad for health. I know people who used to be up in the air on an almost daily basis for years, flying business and first class. Unfortunately one of them is not here anymore, most probably due to DVT.

If I'm not away with the fairies, another way to look at aviation accident statistics is: Today, every major airline suffers from a major accident every 10 years, leading to 2,000 deaths or such per century. So any risk deemed larger than this one must lead to more than 2,000 deaths/century/major airline. I wonder if this could be already demonstrated for excessive sitting (in the current conditions and frequency of flights). Not challenging your theory, just asking.

Yeah good point, looked it up and it is pretty grim, have incorporated in the answer. Thx.

All we could say for this is that we know what historically has taken down airplanes and extrapolate from that data.  This site seems to be a goldmine of data on this (http://www.planecrashinfo.com/cause.htm).
According to these guys if you are involved in a fatal accident involving traveling by commercial aircraft, of the following categories of accidents are most likely to kill you:

58% Pilot/Flight Crew Error
17% Mechanical Failure
9% Sabatoge/Terrorism
6% Weather Related
10% Other Factors

These other factors are a mixed bag ranging from improper loading to bird strikes.
So in theory, the riskiest thing in a commercial aircraft are the guys or gals at the controls of the plane.
But as the odds of being killed in an  commercial airplane crash are extremely slim, somewhere around 1:4,000,000, your most likely killer would simply be old age, illnesses associated with old age or heart disease from such a sedintary lifestyle.


text:
How much operating documentation is produced for an airliner by the manufacturer?
A long, long time ago, when I was a young child, I read in a book or magazine that the 747 weighed 170 tonnes (or whatever) - but that the manuals it came with weighed even more! (I recall the same article explained that the aircraft contained over 100 miles of wiring; it was that kind of article.)
I can well believe that the total amount of technical documentation (design, production, operation, maintenance, etc) associated with an airliner could weigh more than a hundred tonnes.
But, just how much documentation would actually be delivered to the customer? Could it indeed be 170+ tonnes' worth?

Let's imagine 170 tons = 120 tons of paper + 50 tons of covers/binders. With 120 tons of paper we can make 24 millions A4 sheets of 5 g. So 170 tons would represent 48,000 books of 1,000 pages. Let's say we have 4,800 technicians producing the books, each one being specialized in some domain, they need to author/assemble 10 books of 1,000 pages per person. That's a lot.

But, just how much documentation would actually be delivered to the customer? Could it indeed be 170+ tonnes' worth?

The days of delivery of air carrier aircraft technical manuals being delivered by paper manuals are over, so it's certain that 170 tonnes of paper aren't now delivered. Whether or not, if you printed one copy of every manual available and then weighed them, that would reach 170 tonnes per airplane, I have no idea. That sounds a little high though to me, but if you included the weight of all of the engineering paper generated back when they actually produced blueprints, that would certainly be very substantial.
Boeing, as an example, delivers manuals as PDFs, perhaps by other means as well.
A few points:

The carrier gets what they need, and that will vary greatly. For example, if the carrier is receiving a passenger airplane, there's no need for them to have documentation concerning pallet tie down information for the aircraft's main deck.
Manuals need to be updated, and now you just get an current PDF rather than a few pages to be inserted in paper copies you already have.
Individual airplanes get manuals that are customized for that airplane, so you're talking about a lot of different manuals for a model of aircraft.
If the airplane goes through a modification program, the company doing the modification will typically supply manuals (also digitally) that deal with the modification. This is especially true for older passenger aircraft being converted to freighters.

Boeing supplies sample manuals for information expected to be common across variants of a model. Here's a 767-300F sample manual link. Of course, the information in an airplane's individual manuals takes precedence over that in sample manuals.
Perhaps if you printed every copy of every manual of every update, maybe you would get to the weight of a single aircraft of that model.